Manufacture of collapsible tubes and like containers or articles of hardened lead thinly coated with tin



Patented May 1, 1951 UNITED STATES MANUFACTURE OF COLLAPSIBLE TUBES AND LIKE CONTAINERS OR ARTICLES OF HARDENED LEAD THINLY COATED WITH TIN Andr Armand Jules Jean Goifart,

' Brussels, Belgium No Drawing. Application January 5, 1946, Serial No. 639,404. In Germany June 26, 1942 Section 1, Public Law 690, August 8, 1946 Patent expires June 26, 1962 3 Claims. 1

My invention relates to the manufacture of I collapsible packing tubes and like containers or articles of hardened lead thinly coated with tin.

Such containers have heretofore been made of a lead alloy containing antimony. The terms lead alloy or substantially pure lead are used in the specification and claims to designate lead which may contain small quantities of tin, antimony, cadmium, etc.

Some proposals have been made in view of the shortage of tin in order to reduce the thickness of the tin layer but it has been observed that below a given thickness considered as a minimum, the tin-coating is destroyed after a few months even after some weeks and this has been explained by the fact that antimony tends to absorb the tin by diifusion.

The only Way to remedy this drawback has been until now, to use thicker tin-coatings or to add to the aforesaid antimony lead alloy tin in a quantity which is sufiicient for saturating the antimony.

According to my invention the defect described is removed and the quantity of tin which must be used is greatly reduced, by adding to the lead alloy instead of antimony, cadmium, for example in the proportion of 0.3% or 0.4% when collapsible tubes or other articles are manufactured.

It has heretofore been proposed, with reference to the manufacture of lead pipes used for plumbery works made of an alloy of lead, tin and antimony, to add cadmium to this alloy for the purpose of facilitating soldering and giving tractability. The tin-coating of such pipes would however not be attacked (diifused) by the antimony because there is an important proportion of tin in the pipe itself and the tin-coating has a substantial thickness and consequently the phenomenon which is described hereinabove in relation with collapsible tubes must not be taken into consideration.

With my invention, the addition of cadmium gives birth in another kind of manufacturing process to other technical results: a diminution of the quantity of tin which is used and a protection of the very thin tin-coating.

The importance of the invention results from the consideration that for instance in the manufacture of tin-coated collapsible tubes, the quantity of tin used, partly as alloy and partly as coating amounted generally to from 4. to 6% whilst with the process according to the invention, the addition of tin to the lead or to the lead alloy is not necessary and the tin coating may be reduced to a thickness of only 0.4 micron which considering the thickness of the wall of the tube, corresponds to a 0.44% tinning. Moreover, I have observed that even after a year the coating Was quite unharmed.

When cadmium is added to the lead or lead alloy the quantity of tin depends only on the smallest coating which is sufficient for manufacturing the tubes.

I have found that a tin coating of 0.5 micron is adequate for practically all purposes.

Taking into consideration the wastage which is practically unavoidable in the process of manufacture and the tin percentage of which cannot be recuperated in economical conditions the consumption of tin is reduced to 1% compared with about 5% formerly required.

It has been found also that an addition of about 0.4% of cadmium to the lead alloy gives for instance the collapsible tube, the same hardening as the addition of 2% antimony. The cost of the cadmium-alloy being about the same as that of the antimonious alloy, the tin saving realized by the invention is thus a clear profit.

Moreover cadmium and lead melting at the same temperature are very easy to alloy and there is no necessity to cast an intermediate high percentage alloy, as done for antimony.

I have observed also that the few tenths per cent of tin which are supplied into the melt, in which fresh lead is alloyed with cadmium, avoid the risk of spoiling the cadmium by overheating.

What I claim is:

1. In a process of manufacturing collapsible tubes and similar articles formed of a metallic wall of substantially pure lead and a tin coating, the steps of providing substantially pure lead for the metallic wall, adding cadmium thereto, and thereafter coating with a substantially thin tin layer, whereby due to the effect of cadmium the required thinness of the tin layer can be substantially reduced.

2. The process according to claim 1, in which cadmium has been added to the lead in a proportion of 3. As an article of manufacture, a container having walls consisting of an alloy containing a preponderance of lead, and cadmium, and a tin coating upon said walls, the quantity of cadmium contained in the alloy being about ANDRE ARMAND J ULES JEAN GOF'FART.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,301,688 Gurevich Apr. 22, 1919 1,645,098 Friedrich Oct.- 11, 1927 2,088,223 Witte July 2'7, 1937 2,352,384 Hoch June 27, 1944 

